Copper-steel composite commutator bar

Abstract

An electrical commutator having a plurality of spaced apart commutator bars is disclosed. The commutator bars are formed from a composite of an electrically conductive copper portion bonded, for example by brazing or electron beam welding, at an interface to a steel body which is geometrically designed to reduce the bending and longitudinal stiffness of the body, whereby the shear stress at the interface is reduced during operation.

I claim as my invention: 
     
       1. A duplex commutator bar resistant to interfacial delamination due to differential thermal expansion for mounting in an electrical commutator, said bar comprising an elongated iron base alloy body having an upper longitudinal surface and a lower longitudinal surface,   a first plurality of spaced expansion joints extending from said upper longitudinal surface to an interior portion of said body,   a second plurality of spaced expansion joints extending from said lower longitudinal surface to an interior portion of said body and   a solid electrically conducting copper section bonded longitudinally to the upper longitudinal surface of said body along a plurality of separate interface regions between said body and said section.   
     
     
       2. The product of claim 1, wherein said section is electrolytic tough pitch copper and said body is low carbon steel. 
     
     
       3. The product of claim 1, wherein the first plurality of expansion joints and the second plurality of expansion joints are shaped as slots. 
     
     
       4. The product of claim 1, wherein said first plurality of expansion joints extend perpendicularly from said upper longitudinal surface and said second plurality of expansion joints extend perpendicularly from said lower longitudinal surface. 
     
     
       5. The product of claim 1, wherein said first plurality of expansion joints are uniformly spaced and said second plurality of expansion joints are uniformly spaced. 
     
     
       6. The product of claim 5, wherein said first plurality of uniformly spaced expansion joints and said second plurality of uniformly spaced expansion joints are symmetrically arranged in alternating fashion. 
     
     
       7. A duplex commutator bar resistant to interfacial delamination due to differential thermal expansion for mounting in an electrical commutator, said bar comprising an elongated iron-based alloy body having an upper longitudinal surface,   a plurality of spaced expansion joints extending from said upper longitudinal surface to an interior portion of said body, and   a solid electrically conducting copper section bonded longitudinally to the upper longitudinal surface of said body along a plurality of separate interface regions between said body and said section.   
     
     
       8. The product of claim 7, wherein said section is electrolytic tough pitch copper and body is low carbon steel. 
     
     
       9. The product of claim 7, wherein said plurality of expansion joints are shaped as slots. 
     
     
       10. The product of claim 9, wherein said plurality of spaced expansion joints extend perpendicularly from said upper longitudinal surface. 
     
     
       11. The product of claim 7, wherein said expansion joints are uniformly spaced. 
     
     
       12. The product of claim 11, wherein said plurality of uniformly spaced expansion joints extend perpendicularly from said upper longitudinal surface. 
     
     
       13. A duplex commutator bar resistant to interfacial delamination due to differential thermal expansion for mounting in an electrical commutator, said bar comprising an elongated iron base alloy body having an upper longitudinal surface and a lower longitudinal surface,   a first plurality of spaced expansion joints extending from said upper longitudinal surface to an interior portion of said body, said first plurality of expansion joints being narrower towards said upper longitudinal surface and becoming wider toward the medial portion of said body,   a second plurality of spaced expansion joints extending from said lower longitudinal surface to an interior portion of said body, said second plurality of expansion joints being narrower toward said lower longitudinal surface and becoming wider toward the medial portion of said body, and   a solid electrically conducting copper section bonded longitudinally to the upper longitudinal surface of said body along a plurality of separate interface regions between said body and said section.   
     
     
       14. The product of claim 13, where said section is electrolytic tough pitch copper and said body is low carbon steel. 
     
     
       15. The product of claim 13, wherein said first plurality of expansion joints extend perpendicularly from said upper longitudinal surface and said second plurality of expansion joints extend perpendicularly from said lower longitudinal surface. 
     
     
       16. The product of claim 13, wherein said first plurality of expansion joints are uniformly spaced and said second plurality of expansion joints are uniformly spaced. 
     
     
       17. The product of claim 16, wherein said first plurality of uniformly spaced expansion joints and said second plurality of uniformly spaced expansion joints are symmetrically arranged in alternating fashion. 
     
     
       18. A duplex commutator bar resistant to interfacial delamination due to differential thermal expansion for mounting in an electrical commutator, said bar comprising an elongated iron base alloy body having an upper longitudinal surface and a lower longitudinal surface,   a first plurality of spaced expansion joints extending from said upper longitudinal surface to an interior portion of said body, said first plurality of expansion joints being shaped in the form of a round bottomed flask,   a second plurality of spaced expansion joints extending from said lower longitudinal surface to an interior portion of said body, said second plurality of expansion joints being shaped in the form of a round bottomed flask, and   a solid electrically conducting copper section bonded longitudinally to the upper longitudinal surface of said body along a plurality of separate interface regions between said body and said section.   
     
     
       19. The product of claim 18, wherein said section is electrolytic tough pitch copper and said body is low carbon steel. 
     
     
       20. The product of claim 18, wherein said first plurality of expansion joints extend perpendicularly from said upper longitudinal surface and said second plurality of expansion joints extend perpendicularly from said lower longitudinal surface. 
     
     
       21. The product of claim 18, wherein said first plurality of expansion joints are uniformly spaced and said second plurality of expansion joints are uniformly spaced. 
     
     
       22. The product of claim 21, wherein said first plurality of uniformly spaced expansion joints and said second plurality of uniformly spaced expansion joints are symmetrically arranged in alternating fashion.